How to Know Bad Transistors
A transistor is a type of electronic component, more specifically a semiconductor, used as a switch or an amplifier to electronic signals in a circuit. The most well-known use for this device is in a transistor radio. If you have a radio or another device that utilizes this technology, you may have to test the transistor to see if it is the cause of any problems you are experiencing.
- Purchase a multimeter, if you do not already have one.
- Determine the collector to emitter resistance, by placing a multimeter on the resistance setting. You will need to connect the probe to the correct terminal, as well. Look at the packing, if you are unsure of how to identify which one is the emitter and which one is the collector. Switch the probes around and take the reading once again. You should notice a measurement in megaohms, in the case that you do not, your transistor is bad.
- Figure out the forward resistance. Situate the black probe on the emitter and the red probe on the base.
- Switch positions of the probes. The black probe should now be connected to the base and the red probe should be connected to the emitter.
- Evaluate the reverse-to-forward ratio. The reading should not exceed 1000:1. When it is more than that, the transistor is bad.
- Figure out the forward resistance of the collector to base leads. Do so by connecting the collector to the multimeter, the same way you did the emitter in step. Measure the reverse resistance in the same way, only by switching places of the probes.
- Calculate the reverse-to-forward ratio and then assess whether it is lower than 1000:1, if it is then the transistor is good; however, if it more than that ratio, the resistor is bad.